interface/include/psa/crypto_struct.h

/*
 * Copyright (c) 2018-2020, Arm Limited. All rights reserved.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 *
 */
/**
 * \file psa/crypto_struct.h
 *
 * \brief PSA cryptography module: structured type implementations
 *
 * \note This file may not be included directly. Applications must
 * include psa/crypto.h.
 *
 * This file contains the definitions of some data structures with
 * implementation-specific definitions.
 *
 * In implementations with isolation between the application and the
 * cryptography module, it is expected that the front-end and the back-end
 * would have different versions of this file.
 */

#ifndef PSA_CRYPTO_STRUCT_H
#define PSA_CRYPTO_STRUCT_H

#ifdef __cplusplus
extern "C" {
#endif

/*
 * Note that the below structures are different from the decalrations in
 * mbed-crypto. This is because TF-M maintains 'front-end' and 'back-end'
 * versions of this header. In the front-end version, exported to NS
 * clients in interface/include/psa, a crypto operation is defined as an
 * opaque handle to a context in the Crypto service. The back-end
 * version, directly included from the mbed-crypto repo by the Crypto
 * service, contains the full definition of the operation structs.
 *
 * One of the functions of the Crypto service is to allocate the back-end
 * operation contexts in its own partition memory (in crypto_alloc.c),
 * and then do the mapping between front-end operation handles passed by
 * NS clients and the corresponding back-end operation contexts. The
 * advantage of doing it this way is that internal mbed-crypto state is never
 * exposed to the NS client.
 */

struct psa_hash_operation_s
{
    uint32_t handle;
};

#define PSA_HASH_OPERATION_INIT {0}
static inline struct psa_hash_operation_s psa_hash_operation_init( void )
{
    const struct psa_hash_operation_s v = PSA_HASH_OPERATION_INIT;
    return( v );
}

struct psa_mac_operation_s
{
    uint32_t handle;
};

#define PSA_MAC_OPERATION_INIT {0}
static inline struct psa_mac_operation_s psa_mac_operation_init( void )
{
    const struct psa_mac_operation_s v = PSA_MAC_OPERATION_INIT;
    return( v );
}

struct psa_cipher_operation_s
{
    uint32_t handle;
};

#define PSA_CIPHER_OPERATION_INIT {0}
static inline struct psa_cipher_operation_s psa_cipher_operation_init( void )
{
    const struct psa_cipher_operation_s v = PSA_CIPHER_OPERATION_INIT;
    return( v );
}

struct psa_aead_operation_s
{
    uint32_t handle;
};

#define PSA_AEAD_OPERATION_INIT {0}
static inline struct psa_aead_operation_s psa_aead_operation_init( void )
{
    const struct psa_aead_operation_s v = PSA_AEAD_OPERATION_INIT;
    return( v );
}

struct psa_key_derivation_s
{
    uint32_t handle;
};

#define PSA_KEY_DERIVATION_OPERATION_INIT {0}
static inline struct psa_key_derivation_s psa_key_derivation_operation_init( void )
{
    const struct psa_key_derivation_s v = PSA_KEY_DERIVATION_OPERATION_INIT;
    return( v );
}

struct psa_key_policy_s
{
    psa_key_usage_t usage;
    psa_algorithm_t alg;
    psa_algorithm_t alg2;
};
typedef struct psa_key_policy_s psa_key_policy_t;

#define PSA_KEY_POLICY_INIT {0, 0, 0}
static inline struct psa_key_policy_s psa_key_policy_init( void )
{
    const struct psa_key_policy_s v = PSA_KEY_POLICY_INIT;
    return( v );
}

/* The type used internally for key sizes.
 * Public interfaces use size_t, but internally we use a smaller type. */
typedef uint16_t psa_key_bits_t;
/* The maximum value of the type used to represent bit-sizes.
 * This is used to mark an invalid key size. */
#define PSA_KEY_BITS_TOO_LARGE ( (psa_key_bits_t) ( -1 ) )
/* The maximum size of a key in bits.
 * Currently defined as the maximum that can be represented, rounded down
 * to a whole number of bytes.
 * This is an uncast value so that it can be used in preprocessor
 * conditionals. */
#define PSA_MAX_KEY_BITS 0xfff8

/** A mask of flags that can be stored in key attributes.
 *
 * This type is also used internally to store flags in slots. Internal
 * flags are defined in library/psa_crypto_core.h. Internal flags may have
 * the same value as external flags if they are properly handled during
 * key creation and in psa_get_key_attributes.
 */
typedef uint16_t psa_key_attributes_flag_t;

#define MBEDTLS_PSA_KA_FLAG_HAS_SLOT_NUMBER     \
    ( (psa_key_attributes_flag_t) 0x0001 )

/* A mask of key attribute flags used externally only.
 * Only meant for internal checks inside the library. */
#define MBEDTLS_PSA_KA_MASK_EXTERNAL_ONLY (      \
        MBEDTLS_PSA_KA_FLAG_HAS_SLOT_NUMBER |    \
        0 )

/* A mask of key attribute flags used both internally and externally.
 * Currently there aren't any. */
#define MBEDTLS_PSA_KA_MASK_DUAL_USE (          \
        0 )

typedef struct
{
    psa_key_type_t type;
    psa_key_lifetime_t lifetime;
    psa_key_id_t id;
    psa_key_policy_t policy;
    psa_key_bits_t bits;
    psa_key_attributes_flag_t flags;
} psa_core_key_attributes_t;

#define PSA_CORE_KEY_ATTRIBUTES_INIT {0, 0, PSA_KEY_ID_INIT, PSA_KEY_POLICY_INIT, 0, 0}

struct psa_key_attributes_s
{
    psa_core_key_attributes_t core;
#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
    psa_key_slot_number_t slot_number;
#endif /* MBEDTLS_PSA_CRYPTO_SE_C */
    void *domain_parameters;
    size_t domain_parameters_size;
};

#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
#define PSA_KEY_ATTRIBUTES_INIT {PSA_CORE_KEY_ATTRIBUTES_INIT, 0, NULL, 0}
#else
#define PSA_KEY_ATTRIBUTES_INIT {PSA_CORE_KEY_ATTRIBUTES_INIT, NULL, 0}
#endif

static inline struct psa_key_attributes_s psa_key_attributes_init( void )
{
    const struct psa_key_attributes_s v = PSA_KEY_ATTRIBUTES_INIT;
    return( v );
}

static inline void psa_set_key_id(psa_key_attributes_t *attributes,
                                  psa_key_id_t id)
{
    attributes->core.id = id;
    if( attributes->core.lifetime == PSA_KEY_LIFETIME_VOLATILE )
        attributes->core.lifetime = PSA_KEY_LIFETIME_PERSISTENT;
}

static inline psa_key_id_t psa_get_key_id(
    const psa_key_attributes_t *attributes)
{
    return( attributes->core.id );
}

static inline void psa_set_key_lifetime(psa_key_attributes_t *attributes,
                                        psa_key_lifetime_t lifetime)
{
    attributes->core.lifetime = lifetime;
    if( lifetime == PSA_KEY_LIFETIME_VOLATILE )
    {
#ifdef MBEDTLS_PSA_CRYPTO_KEY_FILE_ID_ENCODES_OWNER
        attributes->core.id.key_id = 0;
        attributes->core.id.owner = 0;
#else
        attributes->core.id = 0;
#endif
    }
}

static inline psa_key_lifetime_t psa_get_key_lifetime(
    const psa_key_attributes_t *attributes)
{
    return( attributes->core.lifetime );
}

static inline void psa_set_key_usage_flags(psa_key_attributes_t *attributes,
                                           psa_key_usage_t usage_flags)
{
    attributes->core.policy.usage = usage_flags;
}

static inline psa_key_usage_t psa_get_key_usage_flags(
    const psa_key_attributes_t *attributes)
{
    return( attributes->core.policy.usage );
}

static inline void psa_set_key_algorithm(psa_key_attributes_t *attributes,
                                         psa_algorithm_t alg)
{
    attributes->core.policy.alg = alg;
}

static inline psa_algorithm_t psa_get_key_algorithm(
    const psa_key_attributes_t *attributes)
{
    return( attributes->core.policy.alg );
}

/* This function is declared in crypto_extra.h, which comes after this
 * header file, but we need the function here, so repeat the declaration. */
psa_status_t psa_set_key_domain_parameters(psa_key_attributes_t *attributes,
                                           psa_key_type_t type,
                                           const uint8_t *data,
                                           size_t data_length);

static inline void psa_set_key_type(psa_key_attributes_t *attributes,
                                    psa_key_type_t type)
{
    if( attributes->domain_parameters == NULL )
    {
        /* Common case: quick path */
        attributes->core.type = type;
    }
    else
    {
        /* Call the bigger function to free the old domain paramteres.
         * Ignore any errors which may arise due to type requiring
         * non-default domain parameters, since this function can't
         * report errors. */
        (void) psa_set_key_domain_parameters( attributes, type, NULL, 0 );
    }
}

static inline psa_key_type_t psa_get_key_type(
    const psa_key_attributes_t *attributes)
{
    return( attributes->core.type );
}

static inline void psa_set_key_bits(psa_key_attributes_t *attributes,
                                    size_t bits)
{
    if( bits > PSA_MAX_KEY_BITS )
        attributes->core.bits = PSA_KEY_BITS_TOO_LARGE;
    else
        attributes->core.bits = (psa_key_bits_t) bits;
}

static inline size_t psa_get_key_bits(
    const psa_key_attributes_t *attributes)
{
    return( attributes->core.bits );
}

#ifdef __cplusplus
}
#endif

#endif /* PSA_CRYPTO_STRUCT_H */